Python TypeError: 'tuple' object is not callable when using list comprehension inside for loop

Question

I'm trying to generate a list of strings using a list comprehension, where the string is formatted using f-strings:

features = [("month", (1, 12)), ("day_of_year", (1, 365))]
for feature, range in features:
  cols= [f"transformed_{feature}_period_{i:02d}" for i in range(12)]

If I run this code, I get an error:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[4], line 3
      1 features = [("month", (1, 12)), ("day_of_year", (1, 365))]
      2 for feature, range in features:
----> 3     cols= [f"transformed_{feature}_period_{i:02d}" for i in range(12)]

TypeError: 'tuple' object is not callable

I still get the error even if I remove the variables from the string:

for feature, range in features:
  cols= ["transformed_feature_period" for i in range(12)]

I don't understand why the interpreter is complaining that I'm trying to call a tuple. I'm able to perform other operations, such as actual function calling and asserts inside the outer for loop, but I keep bumping into this error when trying to use a list comprehension.

Thanks in advance for any help.

Answer 1

If you don't actually use the range,

for feature, _ in features:
    ...

If you only care about the endpoints of the range,

for feature, (start, stop) in features:
    ...

If you really need a reference to the tuple as a whole, pick a name that doesn't shadow the built-in type you use later:

for feature, feature_range in features:
    ...

I don't recommend using builtins.range to access the shadowed type when it's simpler to provide a more accurate name for the index variable in the first place.